1. Field of the Invention
The present invention relates, in general, to a tube suitable for use in ex vivo culturing of animal cells and a multiple roller tube cell culture system using the same and, more particularly, to a cell tube having at its opposite end walls two eccentric openings through which culture media can flow in and out. Also, the present invention is concerned with a multiple roller tube cell culture system using a multitude of cell tubes, which is able to culture adherent cells in a continuous or batch type manner with high efficiency.
2. Description of the Prior Art
Conventionally, it is difficult to grow ex vivo cultures of animal cells at high yield and in a concentrated level compared to microorganisms because animal cells which have weak cell membranes and are apt to undergo shear stress. The necessity for animal cell cultures has been increased for various reasons. Various efforts have been made to culture animal cells, but in most such efforts, culture methods for bacteria were applied to the cultures of animal cells irrespective of characteristics of animal cells. Thus, the success of the efforts was not great in spite of much investment.
As a result of recent advances in cell characterization, culture methods have been studied for various cells, especially ES (embryonic stem) cells, hybridoma cells, and CHO (Chinese hamster ovary). Highly concentrated cultures of lymphocyte lineage cells, of which hybridoma cells are representative, can be grown on a membrane by virtue of the development of the hollow fiber system of ASM company. Also, it is possible to culture ES and cancerous cells can be cultured in tissue slices as the rotary cell culture system developed by NASA ensures cell""s undergoing low shear stress and provides environment control.
Cytokines or useful proteins are generally produced from transformed adherent cells, such as CHO, 3T3 or C127, by gene manipulation. The accomplishment of the human genome project allows the expectation that various useful proteins might be produced using adherent cells.
However, mass cultures of adherent cells to which fibroblasts and epithelial-like cells have not yet been developed completely. In fact, culture methods for ES cells or hybridoma cells are applied to the adherent cells, so that not only is the culture yield decreased significantly, but also the adherent cells cannot be cultured for a long time period.
It is an object of the present invention to overcome the problems, encountered in prior arts, of being unable to culture adherent cells for a long period of time and at high yield, and to provide a cell culture system in which adherent cells can be cultured with ease and high productivity.
It is another object of the present invention to provide a method for culturing animal cells on a large scale with high efficiency.
In accordance with an aspect of the present invention, there is provided a cell tube for use in culturing cells, having two openings through which culture media can flow in and out, the openings being eccentrically located on opposite end walls at corresponding positions in contact with the side edges of the end walls.
In accordance with another aspect of the present invention, there is provided a multiple roller tube cell culture system, comprising: one or more cell culture tube bundles, each consisting of a plurality of cell culture tubes axially arranged around the central rotating shaft within a cylindrical housing such that the eccentric opening formed on each end wall of each of the tubes is positioned outward in a radial direction of the housing; an air inlet and an air outlet formed on the housing for feeding oxygen to the interior of the housing; a level controller for maintaining a desired level of cell culture medium inside the housing; a medium inlet for feeding the cell culture medium to the interior of the housing; a plurality of sensors for sensing the pH and dissolved oxygen level inside the housing; and a harvest outlet for automatically discharging culture products from the housing after the cell culturing process is finished.
In accordance with a further aspect of the present invention, there is provided a method for culturing adherent animal cells on a large scale using the multiple roller tube cell culture system, comprising the steps of: feeding a predetermined amount of a culture medium into the cell culture system through the inlet by use of the medium transfer pump under the control of the level controller; rotating the roller drum on which cell tubes are assembled, at a speed of 1 rpm or less to repeatedly bring a portion of cell tubes into contact with the influent medium and air, the cell tube assembly being connected to the axis of the motor; controlling the pH and dissolved oxygen level of the cell culture with the aid of sensors; and increasing the rotation speed to 60 rpm or less to exchange the cell culture with a fresh medium and recover the cell culture.